With an increase in interest in physiological functions of various ingredients contained in food products in recent years, the number of cases in which the Ministry of Health, Labour and welfare of JAPAN authorizes food products containing ingredients contributing to such physiological functions and biological actions as Food for Specified Health Use (FOSHU) is increasing. These food products have been commercialized in the form of daily dishes such as beverages, yogurt, soup, miso soup, and hamburgers as well as tablet candies and tablets, and it has been recommended to take these food products once or twice a day.
Examples of physiological functions include sympathetic nerve inhibiting effect, antioxidant effect, antihypertensive effect, liver function-improving effect and the like, and materials having these functions are sympathetic nerve inhibiting substances, polyphenols, peptides and the like. Humans are subject to stresses from daily lives and their sympathetic nerves are excited as a result, leading to lifestyle-related diseases. Thus, continuous intake of the substances which suppress the excitation of sympathetic nerves has become one of the preventing means for such diseases. Among them, γ-aminobutyric acid is a substance contained in food products and having a high level of safety, and it has been proposed a technique for increasing the content thereof in food products and for adding it to food products (JP-A-2004-147560, JP-A-2003-169659, JP-A-2001-352940, and JP-A-1995-227245).
γ-aminobutyric acid is known to have an antihypertensive effect by which excretion of sodium ions into urine is facilitated in response to excessive ingestion of sodium chloride other than a sympathetic nerve inhibiting effect (Hubert C. Stanton, Archint. Pharmacodyn., 143, p195-204, 1963). Thus, there has been numerous techniques in which γ-aminobutyric acid is used in combination with soy sauce which is a typical food product containing a large amount of sodium chloride (JP-A-2004-187501, JP-A-2002-360289, JP-A-2002-300862, and Japanese Patent No. 3166077). However, since the content of γ-aminobutyric acid within the food product is low, it is necessary to eat a large amount of foods in order to take an effective amount of γ-aminobutyric acid. This leads to the excessive ingestion of sodium chloride, which may result in unfavorable outcomes, meaning the effect of ingesting γ-aminobutyric acid is lessened. In addition, since the production of γ-aminobutyric acid involves the use of a large amount of glutamic acid as a basic ingredient, flavors may be adversely affected by mixing a large amount of γ-aminobutyric acid with a food product depending on a degree of purification.
Examples of substances which have physiological functions include polyphenols. Polyphenols are known to have physiological functions such as an antioxidant effect, an antihypertensive effect, and a liver-function improving effect. In particular, the antihypertensive effect has come to attract attention, and a food product into which polyphenols having such effects are blended was qualified as a Food for Specified Health Use.
In addition, a substance which has physiological functions is peptide. Peptide is known to have physiological functions such as an antihypertensive effect and a liver-function improving effect. In particular, the antihypertensive effect provided by an angiotensin converting enzyme inhibitory effect has come to attract attention, and a food product into which peptide having such effects is blended has been authorized as a Food for Specified Health Use. Lactic acid bacteria beverages containing lactotripeptide, soft drinks containing caseindodecapeptide, powdered soup and processed food (granulated type) containing dried bonito peptide and the like are commercially available.